21111111011 has 8 divisors (see below), whose sum is σ = 21882546048. Its totient is φ = 20345328000.

The previous prime is 21111110981. The next prime is 21111111023. The reversal of 21111111011 is 11011111112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21111111011 - 2¹⁸ = 21110848867 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111110983 and 21111111001.

It is not an unprimeable number, because it can be changed into a prime (21111111031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1405400 + ... + 1420341.

It is an arithmetic number, because the mean of its divisors is an integer number (2735318256).

Almost surely, 2^21111111011 is an apocalyptic number.

21111111011 is a deficient number, since it is larger than the sum of its proper divisors (771435037).

21111111011 is a wasteful number, since it uses less digits than its factorization.

21111111011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2826013.

The product of its (nonzero) digits is 2, while the sum is 11.

Adding to 21111111011 its reverse (11011111112), we get a palindrome (32122222123).

The spelling of 21111111011 in words is "twenty-one billion, one hundred eleven million, one hundred eleven thousand, eleven".